With "brand church" tarnished by child sex abuse and a perception of us only speaking negatively in the public square on "narrow" issues such as same-sex marriage, a conference was convened in Sydney this week to look for answers.

Called Re: Thinking a Public Faith, it was organised by World Vision, the Centre for Public Christianity (CPX) and Arrow Leadership.

The keynote speaker was Yale theologian professor Miroslov Volf (left), who appeared on the ABC1's Q&A program on Monday night.

This was a challenging conference for me to be at because it might be said that ACL's involvement in the public debate about changing the definition of marriage might at times have contributed to some of the "brand damage".

ACL has worked on a broad range of issues but the push to redefine marriage with 11 unsuccessful legislative attempts in the past three years has fuelled perceptions that it’s the only issue we care about.

One of the main messages of the conference was that we are in a post Christian society - a metaphorical pagan "Athens", not theocratic "Jerusalem" - and the sooner Christians get used to this idea the better.

Personally I wonder whether our failure to be all that Jesus intended his church to be to the world and to each other means that Babylonian captivity is perhaps a more appropriate analogy for our current predicament.

But the good news from the Bible is that God's purposes for his people have never been constrained whether in Babylon or Athens - or Rome for that matter.

As Volf said on Q&A, Christianity is at its best when it comes from the margins, not the seat of political power.

Daniel, a Hebrew slave in Nebuchadnezzar's court had influence that changed a world empire.

CPX's John Dickson pointed out that the Apostle Paul locked in Roman prisons did some of his most effective work there for the spread of the gospel, despite his chains.

Pagan and secular states have often done their best (and worst) to suppress the message of Jesus to no long term avail.

It was hostile to some of the "narrow" agendas Christians are perceived to be pursuing, he said.

This is fair comment although I often wonder why it is sometimes difficult to get the media to focus on evidence that does not suit a particular narrative they are pursuing, but that is a discussion for another day.

Another speaker, a Christian from the corporate world, talked about how his business has been reengineered to "solve unsolvable problems" and how this renewed sense of purpose had energised staff, tapping into a human yearning for more than KPIs.

I think this points to something great the church has to offer in terms of providing meaning to people's lives as we see problems in the world.

Solving unsolvable problems will sometimes involve speaking unpopular truths in the public square as well as rolling up our sleeves to help the most marginalised.

Volf painted a vision of a pluralist society where all religions are given space to proclaim, practice and manifest publicly their beliefs under a common roof of a religiously neutral state.

This is fine but we must also be aware that this idea is not embraced with good faith by all players at this point in time.

While we might be post Christian, our society still enjoys the fruits of its Christian roots even as it chops at these very roots.

Christianity may well be heading for further marginalisation.

For this we have examples in Daniel, Jesus and Paul. Daniel refused to bow to the emperor's decree limiting his religious freedom.

Jesus and Paul ran foul of political authorities because they said there was another Lord and it wasn't Caesar. Early Christians were killed in their tens of thousands because of this.

As Volf rightly said, our first allegiance as Christians lies beyond the political state.

His final lecture today on reconciliation was a beautiful treatise on a concept that has the potential to unlock truth, justice and a pathway to restored relationship in our polity which runs counter-cultural to our adversarial political system.

The Bible and history show that, despite the many faults of its adherents, the Jesus cult at its best will always be there for the common good of the material world and for human flourishing.

This will always have private as well as public, political implications.